How is luck related to success?

Luck and success are quite different things. Luck is not your merit, as not your merit a winning the lottery. Luck falls on you just because you're in luck. Although more often lucky those , who knows where and at what time should be - that is, successful people.
Success comes to someone, who deserved it. You knew, what you wanted and you did that you need for it, and you got something that sought: is your success, and it is always with you.
Be lucky is pleasant ans be successful is prestigious.